1. Field of the Invention
The present invention relates to a method of signaling quality of service (QoS) information at a handover between access networks in an IP-based core network, and, more particularly, to a method of signaling QoS information at a handover between access networks in an Internet Protocol (IP)-based core network.
2. Description of the Related Art
A certain amount of resources are reserved to stably provide the resources during a handover (H/O) to guarantee the quality of service of multimedia application during the handover of a mobile node (MN) in a mobile network. Generally, the QoS is affected by a type of the handover.
The type of the handover is classified according to a control signaling load between different entities. That is, the handover is classified as a handover within an identical access router (AR), a handover between access routers (ARs) and a handover between access networks (ANs).
Meanwhile, the signaling load may be differently generated according to the type of the handover in an access network. For example, additional signaling is required according to consideration of the signaling situation when the signaling is achieved based on the resource reservation protocol (RSVP). That is, if an access router is not changed during a handover, a wireless resource is only controlled, but if a previous access router (PAR) is changed to a new access router (NAR), signaling must be achieved to reserve resources on a new path. Also, if a mobility event such as a handover occurs, the QoS is not properly provided until re-reserving resources by transmission of a refresh message between a crossover node (CRN) and a NAR. The CRN is a node at which a previous path and a new path meet.
Therefore, when a mobile node is moved to another access router, the time required to reset a routing path, and the time required to reconfigure resource management, needs to be optimized. That is, resources on the new path should be rapidly reserved, and resources on the previous path should be instantly released.
A main node serving the instant resource reservation and release is the CRN at which the previous path and the new path are met. Therefore, it is very important to quickly find the CRN to rapidly reserve and release the resources. Also, if the CRN is used, the resource re-reservation is achieved only on the new path between the CRN and a NAR, without re-reserving resources in an end-to-end level. Accordingly, a comparatively short delay time is required.
As described above, the resource reservation should be achieved by considering a mobile event such as a handover of a mobile node between access networks in a mobile environment. However, a conventional RSVP cannot be used in the mobile network because the conventional RSVP is designed without considering the mobility event. For overcoming the shortcomings of the conventional RSVP, various solutions have been introduced, such as mobile RSVP (MRSVP), RSVP tunnel, concatenation and optimization for reservation path (CORP), and hierarchical mobile RSVP (H-MRSVP).
The MRSVP provides stable QoS service without delay during a handover of a mobile node. However, the MRSVP ineffectively uses resources in an access network having insufficient resources. According to the MRSVP, a mobile node must previously reserve resources of cells around the area where the mobile mode is transferred, and the reserved resources are not quickly released. Accordingly, the resources are doubly wasted. Furthermore, resources are unnecessarily reserved in an end-to-end level between a sender and a mobile node, or a sender and a proxy agent, because resources are not re-reserved by finding the CRN according to the MRSVP.
The RSVP tunnel provides stable QoS in a tunnel by solving a conventional problem in which a RSVP message is not detected between the end points of tunnel, that is, between a tunnel entry point and a tunnel exit point. However, the RSVP tunnel does not provide a method of rapidly re-reserving resources at a handover of a mobile node, and a method of localized path repair, by instantly finding a CRN. Also, the RSVP unnecessarily performs the resource re-reservation of an end-to-end level.
Meanwhile, the CORP provides a QoS by expanding a conventional RSVP path when a handover occurs. In order to expand the RSVP path, a concatenation for a reservation path is used. However, the CORP wastes resources in a mobile access network having insufficient resources since a terminal must previously reserve resources of cells around the area where the terminal is transferred, and an end-to-end RSVP session is opened without using a node such as a CRN.
The H-MRSVP is a resource reservation protocol unified with the RSVP and a regional registration of a mobile IP. That is, resources are reserved by using a reserve tunnel between a gateway mobility agent (GMA) and a new proxy agent (PA) when an inter-region handover occurs. However, the H-MRSVP has a problem of a lack of resource usability caused by a passive reservation, although the resources are previously reserved only when a handover delay time becomes longer, i.e., when the inter-region handover occurs.